Swap out the default WooCommerce stylesheets for your own

woocommerce_override_css.php

<?php

add_action( 'init', 'woocommerce_overrides', 99 );

function woocommerce_overrides() {
	add_filter( 'woocommerce_enqueue_styles', 'switch_to_theme_css', 10, 1 );
}

function switch_to_theme_css( $styles ) {
    $styles[ 'woocommerce-layout' ][ 'src' ] = get_template_directory_uri()."/assets/css/woocommerce-layout.css";
    $styles[ 'woocommerce-smallscreen' ][ 'src' ] = get_template_directory_uri()."/assets/css/woocommerce-smallscreen.css";
    $styles[ 'woocommerce-general' ][ 'src' ] = get_template_directory_uri()."/assets/css/woocommerce.css";

    return $styles;
}